The present invention relates generally to an IC card and, more particularly, to an IC card having a CardBus shield.
IC cards constructed in accordance with PCMCIA (Personal Computer Memory Card International Association) standards, having a CardBus shield for avoiding signal degradation, such as cross-talk between the contacts in the connector of the card, are well known in the art. Examples of such IC cards are disclosed in U.S. Pat. Nos. 5,833,473; 5,896,274; and 5,940,275.
As disclosed in the aforementioned patents, a CardBus IC card has a dielectric CardBus bridge mounted within the sheet metal enclosure of the card for positioning a 68-position connector mounted at the front end of the card. The bridge is located at the rear of a cutout that opens at the front of the top cover of the enclosure. The bridge supports the front part of the top cover at the rear of the cutout. A CardBus shield is mounted on the top of the connector spaced forwardly from the front edge of the top cover. A raised projection on the forward portion of the CardBus bridge fills in the space between the front edge of the top cover and the rear of the CardBus shield to provide environmental sealing for the interior of the card.
Although the raised projection on the CardBus bridge in the conventional CardBus IC card minimizes the ingress of contaminants into the card and offers some degree of aesthetic continuity, it provides no benefit to the card's rigidity, which is inherently compromised by the cutout formed in the top cover of the card's sheet metal enclosure. This cutout allows the connector portion of the card to flex in an upward and downward rotational direction almost entirely unrestricted. The resulting flexural stresses are transferred to the solder joints between the contacts of the 68-position connector, and the conductive pads on the circuit board within the card, and to the solder joints between the tails on the CardBus shield and ground pads on the circuit board, greatly increasing the likelihood of electrical failure. As a result, conventional CardBus IC cards are intrinsically weaker than standard IC cards.
It is the object of the present invention to provide an improved CardBus IC card that has enhanced structural strength that resists flexural stresses applied to the card, and improves environmental sealing for the card.